Retaining rings with curved surfaces are described. The curved surfaces prevent damage to a fixed abrasive polishing pad when the retaining ring is used in a polishing process. The curved surfaces are on the bottom surface of the ring, such as along the outer diameter and/or along the sidewalls of channels formed in the bottom of the ring.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A retaining ring for chemical mechanical polishing, comprising: an annular ring having a bottom surface configured to contact a polishing pad during polishing, wherein the bottom surface has a plurality of channels, each channel of the plurality of channels defined by sidewalls, wherein corners between the sidewalls and the bottom surface have a first radius of curvature, a corner between an outer diameter of the annular ring and the bottom surface has a second radius of curvature, corners between the sidewalls and the outer diameter have a third radius of curvature that defines a first flared portion of the channel that flares out to a width adjacent the outer diameter, corners between the sidewalls and an inner diameter have a fourth radius of curvature that defines a second flared portion of the channel that flares out to a width adjacent to the inner diameter, the width adjacent the inner diameter of the retaining ring is less than the width adjacent to the outer diameter of the retaining ring, and the sidewalls are substantially parallel to one another along a length of the channel between the first flared portion and the second flared portion.
2. The retaining ring of claim 1 , wherein the first radius of curvature is equal to the second radius of curvature.
3. The retaining ring of claim 1 , wherein the first radius of curvature is at least 120 mils.
4. The retaining ring of claim 1 , wherein a base of the channel is u-shaped.
5. The retaining ring of claim 1 , wherein the channel has a constant depth from the inner diameter to the outer diameter.
6. The retaining ring of claim 1 , wherein the channel is deeper at one end.
7. A method of using the retaining ring of claim 1 , comprising: retaining a substrate with the retaining ring of claim 1 ; applying a polishing liquid to a fixed abrasive polishing pad; and creating relative motion between the substrate and the fixed abrasive polishing pad.
8. A system for chemical mechanical polishing, comprising: a carrier head; a retaining ring attached to the carrier head, wherein the retaining ring comprises an annual portion having a bottom surface configured to contact a polishing pad during polishing, wherein the bottom surface has a plurality of channels, each channel of the plurality of channels defined by sidewalls, wherein corners between the sidewalls and the bottom surface have a first radius of curvature, a corner between an outer diameter of the annular ring and the bottom surface has a second radius of curvature, corners between the sidewalls and the outer diameter have a third radius of curvature that defines a first flared portion of the channel that flares out to a width adjacent the outer diameter, corners between the sidewalls and an inner diameter have a fourth radius of curvature that defines a second flared portion of the channel that flares out to a width adjacent to the inner diameter, width adjacent the inner diameter of the retaining ring is less than the width adjacent to the outer diameter of the retaining ring, and the sidewalls are substantially parallel to one another along a length of the channel between the first flared portion and the second flared portion; and a platen configured to support the polishing pad and retaining ring during polishing.
9. The retaining ring of claim 1 , wherein the first radius of curvature is between 20 and 120 mils.
10. The retaining ring of claim 1 , wherein the fourth radius of curvature is less than the third radius of curvature.
11. The retaining ring of claim 10 , wherein the third radius of curvature is between about 60 and 260 mils.
12. The retaining ring of claim 10 , wherein the fourth radius of curvature is between about 30 and 120 mils.
13. The retaining ring of claim 1 , wherein the first radius of curvature increases from the inner diameter to the outer diameter along the channel.
14. The retaining ring of claim 1 , wherein the plurality of channels are parallel with radii of the retaining ring.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
July 19, 2007
October 11, 2011
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